diff --git a/ets2panda/linter/src/lib/utils/TsUtils.ts b/ets2panda/linter/src/lib/utils/TsUtils.ts
index 7aa8050e888d46cb3c8a07b147c275ea479bc997..3395d32594540e75005beb8ba4593ecbf30bb8cc 100644
--- a/ets2panda/linter/src/lib/utils/TsUtils.ts
+++ b/ets2panda/linter/src/lib/utils/TsUtils.ts
@@ -824,18 +824,22 @@ export class TsUtils {
     isStrict: boolean = false
   ): boolean {
     if (
-      TsUtils.reduceReference(lhsType) === TsUtils.reduceReference(rhsType) &&
-      TsUtils.isTypeReference(lhsType) &&
-      TsUtils.isTypeReference(rhsType)
+      TsUtils.reduceReference(lhsType) !== TsUtils.reduceReference(rhsType) ||
+      !TsUtils.isTypeReference(lhsType) ||
+      !TsUtils.isTypeReference(rhsType)
     ) {
-      const lhsArgs = lhsType.typeArguments;
-      const rhsArgs = rhsType.typeArguments;
-      if (lhsArgs && lhsArgs.length > 0) {
-        if (rhsArgs && rhsArgs.length > 0) {
-          return this.needToDeduceStructuralIdentity(lhsArgs[0], rhsArgs[0], rhsExpr, isStrict);
+      return false;
+    }
+    const lhsArgs = lhsType.typeArguments;
+    const rhsArgs = rhsType.typeArguments;
+    if (lhsArgs && lhsArgs.length > 0) {
+      if (rhsArgs && rhsArgs.length > 0) {
+        if (rhsArgs[0] === lhsArgs[0]) {
+          return false;
         }
-        return this.needToDeduceStructuralIdentity(lhsArgs[0], rhsType, rhsExpr, isStrict);
+        return this.needToDeduceStructuralIdentity(lhsArgs[0], rhsArgs[0], rhsExpr, isStrict);
       }
+      return this.needToDeduceStructuralIdentity(lhsArgs[0], rhsType, rhsExpr, isStrict);
     }
     return false;
   }
diff --git a/ets2panda/linter/test/builtin/builtin_thisArgs.ets b/ets2panda/linter/test/builtin/builtin_thisArgs.ets
index 2a73669055134cc6b5b85d4c122a6da9a8e27bfb..b296e847c11bc4be6bf9ca82359bef48fc1b08f3 100755
--- a/ets2panda/linter/test/builtin/builtin_thisArgs.ets
+++ b/ets2panda/linter/test/builtin/builtin_thisArgs.ets
@@ -28,4 +28,12 @@ let a = new MyClass(2);
 let b = new MyClass(3);
 arr.filter(a.compare, a);
 arr.filter(a.compare);
-arr.filter(a.compare, b);
\ No newline at end of file
+arr.filter(a.compare, b);
+
+type T = number | T[];
+let arr: ReadonlyArray<T> = [[1.0, 2.0], 3.0, [4.0, 5.0]];
+arr.flatMap(
+  (value, index, array) => {
+    return value;
+  }
+);
\ No newline at end of file